will the call_deferred ( String method, … ) return value?

[alexzheng]

**Godot version:3.1 documents

OS/device including version:

Issue description:
In the document it says:
Variant call_deferred ( String method, … ) vararg
Calls the method on the object during idle time and returns the result.

However, it always return null.
Steps to reproduce:

Minimal reproduction project:

[bojidar-bg]

It always returns null (Variant()):

godot/core/object.cpp

Lines 678 to 700 in 1788b22

	Variant Object::_call_deferred_bind(const Variant **p_args, int p_argcount, Variant::CallError &r_error) {
	if (p_argcount < 1) {
	r_error.error = Variant::CallError::CALL_ERROR_TOO_FEW_ARGUMENTS;
	r_error.argument = 0;
	return Variant();
	}
	if (p_args[0]->get_type() != Variant::STRING) {
	r_error.error = Variant::CallError::CALL_ERROR_INVALID_ARGUMENT;
	r_error.argument = 0;
	r_error.expected = Variant::STRING;
	return Variant();
	}
	r_error.error = Variant::CallError::CALL_OK;
	StringName method = *p_args[0];
	MessageQueue::get_singleton()->push_call(get_instance_id(), method, &p_args[1], p_argcount - 1);
	return Variant();
	}

However, create_vararg_method_bind expects a Variant return type:

godot/core/method_bind.h

Line 390 in a7f49ac

MethodBind *create_vararg_method_bind(Variant (T::*p_method)(const Variant **, int, Variant::CallError &), const MethodInfo &p_info) {

Likewise, UndoRedo.add_do_method returns null, but is listed as returning Variant.

[akien-mga]

A quick fix would be to simply change the call_deferred description to be explicit about the fact that it returns null and not the called function's result.

Given the method bind requirements, I'm not sure if we can easily fix this method being advertised as returning Variant() when it's always a null Variant. We have PROPERTY_USAGE_NIL_IS_VARIANT but not PROPERTY_USAGE_VARIANT_IS_NIL :)